A known rotation detecting sensor for detecting rotations of a rotary body (hereinafter referred to as a “rotor”) that includes a magnetic body is disclosed in JP10-318784A and JP2004-177336A. The rotor disclosed forms into the magnetic body having tooth portions (i.e., protruding and recess portions) arranged at predetermined intervals on an outer circumferential surface, for example. The rotation detecting sensor disclosed includes a pair of magnetic elements arranged so as to face the outer circumferential surface of the rotor. The magnetic elements detect rotations of the rotor by detecting a change in magnetic flux that is generated when the protruding and recess portions of the rotor repeatedly approach to, or separate from, the magnetic elements.
In the cases where the pair of magnetic elements is arranged in a direction along the rotation direction of the rotor, signals acquired from the respective magnetic elements are prevented from synchronizing with each other over time. The detected differential between the signals at this time can be used for detecting the rotation speed direction, and the like.
According to the aforementioned rotation detecting sensor, it is important to arrange the pair of magnetic elements in the direction substantially along the rotation direction of the rotor.
For example, in the cases where the rotation detecting sensor is mounted in a specific position or portion in a vehicle, it is required to adjust an angle of the sensor upon mounting, or to manufacture the sensor so as to have a mounting portion suitable for a shape of the portion where the sensor is mounted.
If the pair of magnetic elements are arranged, deviating from the rotation direction of the rotor because of a restriction of the position where the rotation detecting sensor is mounted, a distance between one of the magnetic elements and the rotor, and a distance between the other one of the magnetic elements and the rotor may be significantly different from each other as compared to a case where the pair of magnetic elements are appropriately arranged. In this case, it may be difficult to precisely detect the differential between signals from the respective magnetic elements. Accordingly, the position where the rotation detecting sensor is mounted is restricted because of a requirement of a specific orientation of the magnetic elements.
Normally, the rotation detecting sensors are used in various places in a vehicle for the use of an engine control, an ABS control, and the like. In this case, various and multiple types of rotation detecting sensors are required so as to be suitable for each shape of the portion where the rotation detecting sensor is mounted. That is, multiple types of rotation detecting sensors are present for one vehicle, which leads to a complicated parts control and cost increase.
Thus, a need exists for a rotation detecting sensor that can be mounted in various positions or portions.